Mining activity and habitat use by mountain sheep (<Emphasis Type="Italic">Ovis canadensis</Emphasis>) |
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Authors: | Vernon C Bleich James H Davis Jason P Marshal Steven G Torres Ben J Gonzales |
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Institution: | (1) Sierra Nevada Bighorn Sheep Recovery Program, California Department of Fish and Game, 407 W. Line St., Bishop, CA 93514, USA;(2) School of Animal, Plant and Environmental Sciences, University of the Witwatersrand, Private Bag 3, Wits, 2050, South Africa;(3) Wildlife Investigations Laboratory, California Department of Fish and Game, 1701 Nimbus Road, Rancho Cordova, CA 95670, USA;(4) Present address: Eastern Sierra Center for Applied Population Ecology, 11537 36X Street SW, Suite 102, Dickinson, ND 58601, USA;(5) Present address: 228 Harris Ridge Loop, Kooskia, ID 83539, USA |
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Abstract: | We studied mountain sheep in the vicinity of three high-wall limestone mines in San Bernardino County, CA, USA to evaluate
factors that influenced habitat use and, specifically, to investigate the influence of mining activity on distribution of
those specialized ungulates. We used aerial telemetry data to estimate a resource selection function by fitting a logistic
regression model and then comparing environmental characteristics at observed sheep locations to those at random locations.
Distribution of mountain sheep was most influenced by a fire in 1999 that resulted in an area they avoided. Mountain sheep
used steeper slopes, areas of lower terrain roughness, higher elevations, and areas closer to escape terrain than were random
points. In contrast, sheep avoided areas near roads (federal and state highways, local roads, and off-road vehicle trails)
but used areas near hiking trails and a railway. Water sources had the smallest effect of the factors considered, with sheep
being associated with areas further from water points than were random locations. The disturbed area associated with the mines
had a moderate influence on distribution, with sheep being associated with areas closer to the mine than were random points.
Mining activities can alter terrain features and vegetation structure or composition in a way that promotes occupancy by sheep
if they create steep slopes and rugged terrain (escape terrain) or reduce vegetation density or height (i.e., improve visibility).
Whether increased occupancy reflects a benefit depends on the demographic responses of those sheep to the resources and conditions
available on mine sites; information about those responses remains lacking. |
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Keywords: | Bighorn sheep California Disturbance Habitat selection USA |
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